A locking device for a door with a rigid frame, which consists of a drive rod lock and a door catch mechanism, is known from German Patent Publication DE-C-3 503 466. The drive rod lock has a drive rod coupled with a bar actuating device. In this case the drive rod is used, on the one hand, for the mechanical coupling of the main lock with at least one additional lock. On the other hand it is used to push a bolt of the door catch mechanism from an engagement position to a released position. Displacement of the bolt into the engagement position takes place via a toothed wheel gear. A cone is disposed on the drive rod in the area of the bolt. The cone is guided along a pin connected with the bolt by the movement of the drive rod and is pushed into the release position by this. By this technique the bolt is released from a pivot shackle, which is connected with a rigid frame bordering the door.
It is disadvantageous that in the course of an unlocking movement for releasing the door that the entire drive rod must also be moved. Furthermore, an additional force must be applied pushing the bolt back. It is furthermore disadvantageous that it is necessary to perform uncoupling with respect to the additional locks because of the employment of the drive rod as door catch release element. If this uncoupling does not take place, it additionally makes the actuation of the locking device more difficult when opening the door.
Another drive rod lock is known from German Patent Publication DE-C-3 836 693 and has a center lock attached to a cuff plate. A drive rod-activated additional lock extends above it. A center lock catch and a blocking element of the additional lock can be synchronously displaced into an opening position by the follower of the center lock as well as by key actuation of the latter. A slide, which is controlled by the strike plate, has a catch ramp and is prestressed by a spring in an outward direction and is assigned to the blocking element of the additional lock for releasing the additional blocking element, which is captive in the retracted position and extends for actuation of the drive rod when it is released. The pre-stressed slide is intended to improve the security of the door without a key actuation after it has been pulled shut.
A further drive rod lock is known from German Patent Publications DE-A-3 831 529 and DE-A-4 114 007, wherein a bar/drive rod locking unit is operated by means of a handle follower. A bar and the drive rod with additional locks is operated by turning the handle follower. Blocking of the bar/drive rod locking unit takes place with the aid of a key, so that displacement out of its locking position into an open position is prevented.
Now, if a door in which such a drive rod lock is disposed is additionally provided with a door catch mechanism, a release position cannot be achieved with the aid of the drive rod, because opening of the door is performed by door handles on both sides of the door. Coupling such an opening process with a displacement of the bolt of the door catch mechanism into a released position would inevitably lead to the ineffectiveness of the door catch mechanism.
But uncoupling would result in that a door which can be unlatched would nevertheless remain locked, because in the engagement position the bolt does not release the pivot shackle of the door catch mechanism.